The circuit diagram of a full wave rectifies:
A centre tap transformer and two identical divides ${\mathit{D}}_1$ and ${\mathit{D}}_2$ are used to diagram a full wave rectifies. The centre-tap transformer has 3 output terminals. Centre tap is $\mathrm{C}$ is always at $\mathrm{OV}$.
Drawing positive half cycle of $\mathrm{AC},\mathrm{A}$ is +ve and $\mathrm{B}$ is $-\mathit{v}\mathit{e}$. For negative half cycle, B is + ve and A is - ve. So, when positive half cycle appears, A is +ve, B is $-\mathit{v}\mathit{e}$ and $\mathrm{c}$ is $\mathrm{O}$.
So, divide ${\mathit{D}}_1$ is forward biased and divide ${\mathit{D}}_2$ is reverse biased.
When negative half cycle appears,
$\mathrm{A}$ is -ve, $\mathrm{B}$ is + Ve and $\mathrm{C}$ is $\mathrm{O}$
So, divide ${\mathit{D}}_2$ is forward biased and divide ${\mathit{D}}_1$ is reverse biased.
So, for each half cycle one divide conducts current through ${\mathrm{R}}_{\mathrm{L}}$ flows unidirectionally. Hence the voltage developed across ${\mathit{R}}_{\mathit{L}}$ is a DC.